Topical natamycin tied to better visual acuity, fewer adverse events for treatment of fungal keratitis: Study

UK: According to new research by Jeremy J. Hoffman, therapy with natamycin is associated with considerably higher visual acuity and fewer adverse effects when compared to treatment with chlorhexidine for fungal keratitis. The findings of this study were published in the journal Ophthalmology on 08th December 2021.

The goal of this study was to see if topical chlorhexidine 0.2 percent, which is inexpensive and simple to make, is non-inferior to topical natamycin 5% for the treatment of filamentous fungal keratitis.

This was a non-inferiority clinical study that was randomized, controlled, and single-masked. Adults attending a tertiary-level ophthalmic hospital in Nepal with filamentous fungal infection verified on smear or confocal microscopy were chosen as subjects. Participants were assigned at random to either topical chlorhexidine 0.2 percent or topical natamycin 5%. The primary analysis (intention-to-treat) was carried out using linear regression with baseline logMAR best spectacle-corrected visual acuity (BSCVA) and treatment arm as pre-specified covariates. The initial study omitted mixed fungal-bacterial infections, however, they were included in additional analyses and secondary safety-related outcomes. The margin of non-inferiority was 015 logMAR.

The findings of this work were as follow:

1. Primary outcome data for 153 and 151 of the chlorhexidine and natamycin groups, respectively, were available.

2. Mixed bacterial-fungal infections were discovered in 20 of these instances (12/153 chlorhexidine, 8/151 natamycin) and were eliminated from the original study.

3. As a result, 284 individuals were evaluated for the main outcome (141 chlorhexidine, 143 natamycin).

4. Researchers found no indication that chlorohexidine was non-inferior to natamycin, and in fact, after controlling for baseline BSCVA, they found strong evidence that natamycin-treated subjects had considerably superior three-month BSCVA than chlorhexidine-treated people.

5. After controlling for baseline ulcer depth, the chlorhexidine arm had more perforations and/or emergency corneal grafts than the natamycin arm, but natamycin-treated patients were less likely to perforate and/or require an emergency corneal transplant.

In conclusion, Natamycin is better than chlorhexidine as first-line therapy for filamentous fungal keratitis, and this study emphasizes the need of making it widely available in all countries where FK is a public health problem. More research is needed to determine whether lower dosages of chlorhexidine or combination treatment with natamycin may be used to treat fungal keratitis.

Reference: Topical chlorhexidine 0·2% versus topical natamycin 5% for the treatment of fungal keratitis in Nepal: a randomized controlled non-inferiority trial. Hoffman, Jeremy J. et al. DOI:https://doi.org/10.1016/j.ophtha.2021.12.004